WASHINGTON — US jets and drones launched more airstrikes in northern Iraq on Thursday to destroy vehicles operated by extremist fighters from the so-called Islamic State, the military said.

The latest operations came after President Barack Obama said the air campaign had achieved its initial objectives but warned of more strikes to protect US personnel in the Kurdish city of Arbil.

US Central Command said drones and fighter jets took part in the latest strikes, the first at 1505 GMT to take out two armed trucks that had been firing on Kurdish forces.

The second strike took place just over 30 minutes later, targeting an MRAP — a heavy armored truck of the type supplied by Washington to Iraqi forces and presumably captured by IS forces in recent months.

“All aircraft exited the strike area safely,” Centcom said.

Since July, Sunni jihadist fighters have seized a swathe of northern Iraq including the city of Mosul, routing Shiite-led Iraqi forces and driving out wave of refugees from the minority Christian and Yazidi communities.

Now, the IS advance threatens Arbil, the capital of Iraq’s autonomous Kurdish region and host to a US consulate and other facilities. Obama, while ruling out sending US combat troops, has vowed to protect it.